1. Field of the Invention
This invention relates to a compact retrofocus type wide angle lens.
2. Description of the Prior Art
As wide angle lenses for single lens reflex cameras, use is generally made of the so-called retrofocus type lenses which can provide a back focal length long as compared with the focal length. However, the construction of the retrofocus type lens is asymmetrical with respect to the stop and therefore, aberration correction is difficult and the degree thereof becomes stronger as the angle of view becomes greater. To meet the requirement of interchangeable lenses for compactness and greater aperture ratio as the recent tendency, aberration correction tends to be more difficult. That is, if the refractive power of the divergent group disposed adjacent to the object side is strengthened for the purpose of compactness, various aberrations such as spherical aberration and coma created in each lens are aggravated, and this tendency becomes stronger with an increase in aperture. In a wide angle lens having an angle of view of 94.degree., a construction in which the number of negative lenses constituting the divergent group is increased is known, for example, from British Patent No. 1,238,668 or U.S. Pat. No. 4,348,085, but this construction has suffered from a disadvantage that the full length of the lens system increases and the forward lens system becomes bulky. In addition, it has involved many difficulties under the influence of high-order aberrations to correct chromatic difference of magnification well over a wide angle of view, and many of the known lenses of this type have been insufficient because of the deterioration of the marginal image relative to the center of the picture plane or the blur of colors.